1. Field of the invention
The present invention relates to a line driving circuit of a semiconductor device, and more particularly to a line driving circuit for reducing the swing width of a transmission signal.
2. Description of the Prior Art
As generally known in the art, data transmission between interior circuits in a semiconductor device is achieved through transmission lines connected between the interior circuits.
A line driving circuit generally refers to a circuit for transmitting data (or signals) from an interior circuit to another interior circuit through a transmission line.
Hereinafter, a line driving circuit will be described with reference to FIGS. 1A and 1B.
FIG. 1A is a block diagram illustrating a state in which different interior circuits are connected to each other through transmission lines, and FIG. 1B is a circuit diagram illustrating the last circuit of an interior circuit shown in FIG. 1A.
As shown in FIG. 1B, typically, the last circuit of an interior circuit includes an amplification unit and drivers. Herein, the amplification unit may include a differential amplifier or the like, and each of the drivers 11 and 12 typically includes a CMOS inverter or the like. In FIG. 1B, “CLK_LATCH” represents an enable signal, “in” and “inb” represent signals applied to the amplification unit, and “out1” and “out1b” represent output signals of the amplification unit. Also, “out” represents the output node of an interior circuit shown in FIG. 1A, and is connected to a transmission line.
In operation, a signal applied to the amplification unit is amplified by the differential amplifier, and then is applied to the drivers 11 and 12 via inverters. The drivers 11 and 12 transmit the VDD and the ground voltage to an interior circuit through a transmission line connected to the output node ‘out’. Therefore, the signal transmitted through the transmission line is a signal swinging fully between the voltage of VDD and the ground voltage.
Herein, the power of a signal transmitted through the transmission line is expressed as the following equation.P=(½)*C*VDD*VDD*f*N
Herein, ‘P’ represents a power, ‘C’ represents the capacitance of a transmission line, ‘VDD’ represents a supply voltage, ‘f’ represents the frequency of a transmission signal, and ‘N’ represents the number of transmission lines.
However, when a typical CMOS-type inverter driver is used as a line driving circuit as described with reference to FIG. 1, a signal transmitted through a transmission line swings fully between the VDD and the ground voltage, so that power consumption required in the transmission line increases.